Readers Respond to "Bigger Cities Do More with Less" and Other Articles

WHY CITIES SUCCEED
In “Bigger Cities Do More with Less,” Luís M. A. Bettencourt and Geoffrey B. West assert that a high-rent city allows only greatly value-adding activities to be profitable, which leads to a cycle in which more talent is attracted, “pushing rents higher still, fueling the need to find yet more productive activities.” The serious downside of higher commercial property rents is that many small businesses, such as barbershops, dry cleaners and convenience stores, are forced out of residential neighborhoods. There are many services that cannot be acquired through the Internet.Ronald BourqueBrooklyn

Bettencourt and West seem perplexed that the San Francisco Bay Area and the Boston region outperform other, similar urban conglomerations. They attribute this to “cer­tain intangible qualities of social dynamics—rather than the development of material infrastructure.” I would suggest that although Harvard University, the Massachusetts Institute of Technology, Stanford University and the University of California, Berkeley, do instill certain intangible qualities in their students, these institutions are very much “material infrastructure” and probably explain a lot of the difference in economic development.Lee OtterholtLaguna Beach, Calif.

The correlation Bettencourt and West make between patents and population confuses cause and effect. Cities mostly grow because innovative companies are successful and attract employees from all over the world, not because an urban environment spurs innovation. Here in Silicon Valley most of the innovation comes from midpeninsula suburban cities between San Francisco and urban San Jose. And companies here and in Dallas strive for an informal campus style of construction with open spaces. Innovation comes from synergy among entrepreneurship, available venture capital, access to universities, a mobile and diverse workforce, and a place where people want to live.Ben RobertsSunnyvale, Calif.

SUPERTALL SCRUTINY
In presenting the changes that have occurred in the design of skyscrapers since September 11, 2001, in “Castles in the Air,” Mark Lamster notes three threats: aircraft impact, earthquakes and wind. He correctly claims that structural engineers are now able to effectively design against them.

Unfortunately, the Twin Towers collapsed primarily because of fire, and nowhere in the article is fire explicitly mentioned as a structural threat. On 9/11 we clearly saw that fire can cause entire modern high-rise buildings to collapse. (Indeed, 7 World Trade Center, a steel-framed high-rise, was not struck by an aircraft but collapsed because of fire ignited by debris from the Twin Towers.) To ensure safety in ever taller buildings, the potential impacts of uncontrolled fire need to be explicitly considered during the structural design process with the same care as earthquakes and wind. While changes in escape-stair width, firefighter communications systems and the addition of sky bridges (all noted by Lamster) can only improve life safety in tall buildings, they do not prevent structural collapse resulting from fire.

Preventing another 9/11 requires that the structural engineering and architecture communities own up to the reality of what uncontrolled fire can do to tall buildings and take the necessary actions.Luke BisbySenior Research Fellow in Structures and Fire
University of Edinburgh

Lamster mentions that the Bank of America Tower in New York City “creates two thirds of its own energy” with a gas generator. But it depletes our unquestionably finite supply of natural gas to generate that energy.Bill ChristianNorth Bennington, Vt.